package sword2offer;

import java.util.Stack;

class CQueue {
    private Stack<Integer>stack1;
    private Stack<Integer>stack2;
    public CQueue() {
        stack1=new Stack<>();
        stack2=new Stack<>();
    }

    public void appendTail(int value) {
        stack1.push(value);
    }

    public int deleteHead() {
        if (stack2.isEmpty()){
            if (stack1.isEmpty())return -1;
            while (!stack1.isEmpty()){
                stack2.push(stack1.pop());
            }
        }
        return stack2.pop();
    }
}